Timber Strength Class C24: Properties and Uses
Strength class C24 timber carries a characteristic bending strength of 24 newtons per square millimeter. These are the numbers structural design starts from.
Characteristic bending strength: 24 N/mm²
| Strength class | C24 |
| Characteristic bending strength | 24 N/mm² |
| Mean elastic modulus | 11 GPa |
| Characteristic density | 350 kg per cubic meter |
| Typical source | good structural softwood, the floor joist standard |
Notes for design and site
C24 is the default for floors, flat roofs, and anything span sensitive: half again the strength of C16 and nearly forty percent more stiffness for a modest premium. Imported redwood and whitewood machine grade to C24 reliably, and most span tables in common use assume it.
Related Calculators and Reference
- Property Library: the full materials reference on this site.
- Bill of Quantities Builder: price the timber package properly.
- Eurocodes at the JRC: the design standards behind these classes.